Foot for the sewing of blind stitches on sewing machines

ABSTRACT

A foot for the sewing of blind stitches comprises a substantially vertically arranged shank portion having a lower end connected to a substantially flat foot sole which extends outwardly from the shank portion and which includes a toe part having an upturned forward end for guiding the material thereunder. The foot sole also includes a narrow short intermediate web which terminates rearwardly of a needle slot formed between the web and an inturned portion of a forwardly extending elastic stop arm. The stop arm is widened at its front end ahead of the intermediate narrow short web and it includes a downturned face opposite to the toe part which forms a guide tongue for guiding the material which is fed toward the needle which reciprocates in a slot located between the rear end of the laterally extending portion of the stop and the front end of the intermediate short web portion.

United States Patent [191 Meier [111 3,817,195 June 18, 1974 FOOT FOR THE SEWING OF BLIND STITCHES ON SEWING MACHINES Inventor: Giinter Meier, Weingarten,

Germany Assignee: Pfaff Haushaltsmaschiner GmbH,

Karlsruhe-Durlach, Germany Filed: Feb. 21, 1973 Appl. No.: 334,280

Foreign Application Priority Data Mar. 15, 1972 Germany 7209847 US. Cl. 112/235, 112/150 Int. Cl D05b 29/00 Field of Search 112/235, 60, 61, 150, 151

References Cited UNITED STATES PATENTS 6/1939 Boguhn et a1 112/151 9/1953 Enos 4/1956 Smith 112/235 Primary Examiner-Richard J. Scanlan, Jr. Attorney, Agent, or Firm-McGlew and Tuttle [5 7] ABSTRACT A foot for the sewing of blind stitches comprises a substantially vertically arranged shank portion having a lower end connected to a substantially flat foot sole which extends outwardly from the shank portion and which includes a toe part having an upturned forward end for guiding the material thereunder. The foot sole also includes a narrow short intermediate web which terminates rearwardly of a needle slot formed between the web and an intumed portion of a forwardly extending elastic stop arm. The stop am is widened at its front end ahead of the intermediate narrow short web and it includes a downturned face opposite to the toe part which forms a guide tongue for guiding the material which is fed toward the needle which reciprocates in a slot located between the rear end of the laterally extending portion of the stop and the front end of the intermediate short web portion.

5 Claims, 3 Drawing Figures FOOT FOR THE SEWING OF BLIND STITCHES ON SEWING MACHINES BACKGROUND OF THE INVENTION 1. Field of the invention This invention relates in general to the construction of sewing machines and, in particular, to a new and useful foot for the sewing of blind stitches on sewing machines which includes a stop formation on an elastic arm portion of the foot sole.

2. Description of the prior art When sewing blind stitches on a z ig-zag sewing ma chine, the upper fold edge of the workpiece folded in an overlapped or zig-zag sectional form is pierced at a small distance from the outer side of the fold edge corresponding, for example, to half of the cloth thickness, so that after the turning back of the workpiece part lying at the top during sewing, the seam is not visible from the side. In order to maintain the precise spacing of the workpiece from the needle by the exactly determined distance from the outer end of the upper fold edge during sewing, the fold edge is guided along a guide face of a stop which is elastic in a vertical plane. Several types of feet for the sewing of blind stitches are known. Thus, for example, sewing feet where the guide face of the elastic stop is covered are known, and with such feet, the part of the fold edge of the workpiece to be pierced, which is adjacent to the guide face, is covered. The operator of the sewing machine, therefore, cannot check in a proper manner whether the fold edge actually runs along the guide face as it should. In other known sewing feet, the stop is elastic so that itmay bend around axes which extend parallel to the feed direction of the workpiece. The stop, therefore, moves only approximately in a vertical plane. The result of this is that the lateral distance between the guide face of the stop and the movement path of the needle varies as a function of the size of the spring path of the stop.

SUMMARY OF THE INVENTION In accordance with the invention, there is provided a foot for the sewing of blind stitches which does not have the disadvantages of the prior art, and which includes a stop with a guide tongue for the fold edge to be pierced which is exposed and is elastically movable in a vertical plane which extends parallel to the feed direction of the workpiece. With the inventive construction, the stop is designed as an arm which is connected with the sewing foot laterally of the shank portion and which extends outwardly from the righthand side of the shank portion when viewed in the feed direction of the material. The arm presents a flat cross-section and is connected laterally of the shank of the sewing foot and preferably in the zone of the rear end of the sewing foot. It extends outwardly parallel to the toe portion of the sewing foot and is provided with a guide tongue at the end of a relatively long arm which extends substantially parallel to the toe. This permits an elastic bending of the arm even whenthe small forces act thereon. The flat, preferably rectangular cross-section of the arm ensures that it will be bent only in a vertical plane and, in a horizontal plane, it is relatively stiff.

Since inblind stitch sewing, the foot sole rests only on the upper cloth layer of the work and on the side of the workpiece which is to the right of the upper fold edge in respect to the feed direction of the work is disposed at a vertical distance below the upper cloth layer, the blind stitch sewing foot of the invention includes a foot sole with a toe portion which extends only on the left side of the guide tongue which is carried by the stop arm. Thus, the stop arm carrying the guide tongue can be arranged at the level of the foot sole and closely alongside the same. The guide tongue is then arranged on the left side of the arm facing the foot sole so that the left side of the guide tongue, which forms the guide face for the upper fold edge, is exposed.

The stop may be made of a sheet metal material, for example, and maybe secured to the sewing foot such as by suitable screws, or if suitable material is selected, it may be soldered to the sewing foot. Alternatively, the sewing foot shank and the foot sole may be made of a single plastic piece by injection molding or, the rear end of the sheet metal stop may be clad with a plastic material. In a preferred construction, the sewing foot is made of a one-piece plastic injection molded part. In this case, the entire sewing foot can be produced in a single operation. By proper selection of the dimensions, it can be arranged that the foot sole is stiff and the stop, as mentioned, can be elastically deformable in a vertical plane.

In accordance with a further aspect of the invention, the arm carrying .the stop has a notch adjacent its rear end which extends transverse to the feed direction of the work. This makes the arm resilient or bendable, particularly in the region of the notch. The construction makes it possible for the arm to deviate elastically from its normal position when relatively small vertically directed forces act on it and, consequently, the guide tongue rests on the work with only slight force, even in the case of thick material.

It is possible by the use of a notch formation at the inner end of the arm to make it of relatively short length and without interfering with its elastic characteristic.

An object of the invention is to provide an improved sewing foot for the sewing of blind stitches, which comprises a shank portion, a foot sole portion connected to the shank portion and an elastic stop portion connected to the shank portion which includes a downwardly extending guide tongue with a vertically exposed guide face and wherein the stop portion comprises an arm of flat cross-section and is located on the righthand side of the foot sole when seen in the feed direction.

A further object of. the invention is to provide a sewing foot for sewing of blind stitches which is simple in design, rugged in construction, and economical to manufacture.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF TI-IEDRAWINGS In the Drawings: FIG. 1 is a front perspective view of a sewing machine foor for the sewing of blind stitches;

FIG. 2 is aside elevational view of the foot shown in FIG. 1, but on a reduced scale; and FIG. 3 is a bottom plan view of the foot shown in FIG.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in particular, the invention embodied therein, comprises a foot for sewing machines for the sewing of blind stitches, and, in the embodiment illustrated, itcomprises a single piece, generally designated 1, which is formed as an injectionmolded part. The foot 1 includes a vertically oriented shank portion 1a with a horizontally extending sole or foot sole, generally designated 2. The foot sole 2 includes a toe portion 4 extending substantially horizontally outwardly from the lower end of the shank portion la and which includes an upturned end extending in an opposite direction to the feed direction N for the workpiece ll. The foot sole 2 also includes a short web portion 5, having a front edge which is spaced from the rear edge of an inturned forward portion of a stop, generally designated 3. Between the stop and the short web 5, there is a cutout or slot 6, through which the needle 7 passes during operation;

The stop 3 comprises an elongated arm 8 which extends parallel to the feed direction end and which is widened in the region of its front end in a direction toward the toe portion 4. The widened area of the arm 8 carries a guide tongue 9 having a substantially vertically extending guide surface which faces toward the toe 4. The arm 8 is connected to the remainder of the foot sole 2 on the right side of the shank 1a when viewed in the direction of the feed N. The arm 8 has a flat rectangular cross-section, so that it is elastic in a vertical plane, but is relatively stiff in a horizontal plane. ln addition, in accordance with a feature of the invention, the underside of the arm 8 is provided with a cross-notch 10 which permits the elastic deformation of the arm, particularly in the region of the notch 10. Because of this construction, the arm 8 will give elastically under relatively small vertically acting forces. Consequently, the guide tongue 9, whose bottom surface rests on the top of the material, will be moved resiliently upwardly and downwardly in order to accommodate the variations in the thickness of the material.

The workpiece 11 to be treated is folded in an overlapped arrangement to form a Z-shape configuration in side elevation, and the outer side of the upper fold edge 12 is always directed toward the right. Therefore, the left side face of the guide tongue 9, facing the toe portion 4, forms the guide face 13 for the fold edge 12.

As can be seen'from FIGS. 1 and 3, the guide face 13 is exposed. The alignment and the distance of the fold edge 12 relative to the guide face 13 can thus be controlled without any difficulty. The arrangement is such that the operator can always guide the fold edge 12 at a constant distance from the movement path of the needle 7 and this is true even in the case of workpieces of different thicknesses. The needle 7 is thus able to pierce the folded edge 12 exactly at a distance from the outer side of the fold edge corresponding to half of the cloth thickness.

Another aid for the exact guiding of the workpiece 11 is formed by the triangular incision 14 which is made inwardly along the forward edge of the front end of the arm 8. The triangular incision 14 forms a guide under which the workpiece edge 15 or a marking line can be centered.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A foot on sewing machines for the sewing of blind stitches comprising a shank portion, a flat foot sole portion connected to said shank portion, and a flat arm elastic stop portion connected to said shank portion, said elastic stop portion having a downwardly extending guide tongue with a vertically exposed guide face, said stop portion comprising an arm of flat crosssection which extends in respect to the feed direction of the workpiece on the right side of said foot sole portion, said arm being connected with said foot sole portion laterally of said shank portion.

2. A foot on sewing machines for the sewing of blind stitches, according to claim 1, wherein said foot comprises a one-piece plastic injection molded part.

3. A foot on sewing machines for the sewing of blind stitches, according to claim 1, wherein said arm portion has a transverse bending area notch in the region of its rear end in respect to the feed direction.

4. A foot for the sewing of blind stitches, comprising a one-piece injection-molded part substantially vertical shank portion, a flat foot sole extending outwardly from the lower end of said shank portion and having an outwardly extending substantially horizontal toe part, an outwardly extending intermediate narrow web portion and an elastic stop portion extending outwardly from said shank portion generally parallel to said toe part and having a downwardly extending guide tongue facing said toe part with a vertically exposed guide face.

5. A foot for the sewing of blind stitches, according to claim 4, wherein said elastic stop portion extends substantially parallel to said intermediate portion and said toe portion and includes an inturned forward transversely extending portion spaced ahead of said intermediate narrow webportion in a direction opposite to the feed direction of the material, said narrow web portion and said toe part defining a slot therebetween for the passage of the needle, said transversely extending portion having a downwardly extending guide tongue facing said toe portion with a vertical exposed guide facing and having a forward edge with a notch forming a guide for orienting the workpiece therebelow. 

1. A foot on sewing machines for the sewing of blind stitches comprising a shank portion, a flat foot sole portion connected to said shank portion, and a flat arm elastic stop portion connected to said shank portion, said elastic stop portion having a downwardly extending guide tongue with a vertically exposed guide face, said stop portion comprising an arm of flat cross-section which extends in respect to the feed direction of the workpiece on the right side of said foot sole portion, said arm being cOnnected with said foot sole portion laterally of said shank portion.
 2. A foot on sewing machines for the sewing of blind stitches, according to claim 1, wherein said foot comprises a one-piece plastic injection molded part.
 3. A foot on sewing machines for the sewing of blind stitches, according to claim 1, wherein said arm portion has a transverse bending area notch in the region of its rear end in respect to the feed direction.
 4. A foot for the sewing of blind stitches, comprising a one-piece injection-molded part substantially vertical shank portion, a flat foot sole extending outwardly from the lower end of said shank portion and having an outwardly extending substantially horizontal toe part, an outwardly extending intermediate narrow web portion and an elastic stop portion extending outwardly from said shank portion generally parallel to said toe part and having a downwardly extending guide tongue facing said toe part with a vertically exposed guide face.
 5. A foot for the sewing of blind stitches, according to claim 4, wherein said elastic stop portion extends substantially parallel to said intermediate portion and said toe portion and includes an inturned forward transversely extending portion spaced ahead of said intermediate narrow web portion in a direction opposite to the feed direction of the material, said narrow web portion and said toe part defining a slot therebetween for the passage of the needle, said transversely extending portion having a downwardly extending guide tongue facing said toe portion with a vertical exposed guide facing and having a forward edge with a notch forming a guide for orienting the workpiece therebelow. 